Looper drive for chain stitch sewing machines



Nov. 15, 1966 w. TRETOW ETAL 3,285,210

LOOPER DRIVE FOR CHAIN STITCH SEWING MACHINES Filed Oct. 8, 1963 5 Sheets-Sheet 1 Q LL.

lo I\ IN VEN 7OR5 1 Wile/v59 narrow 44 0 1966 w. TRETOW ETAL LOOPER DRIVE FOR CHAIN STITCH SEWING MACHINES 5 Sheets-Sheet 2 Filed Oct. 8, 1963 1966 I w. TRETOW ETAL 3,285,210

LOOPER DRIVE FOR CHAIN STITCH SEWING MACHINES Filed Oct. 8, 1963 5 Sheets-Sheet 3 Nov. 15, 1966 w. TRETOW ETAL 3,285,210

LOOPER DRIVE FOR CHAIN STITCH SEWING MACHINES Filed 001:. 8, 1963 5 Sheets-Sheet 4 Nov. 15, 1966 w. TRETOW ETAL LOOPER DRIVE FOR CHAIN STITCH SEWING MACHINES 5 Sheets-Sheet 5 Filed Oct. 8, 1963 Fig.6

United States Patent 3,285,210 LOOPER DRIVE FOR CHAIN STITCH SEWING MACHINES Werner Tretow, Kaiserslautern, Pfalz, and Hans Orth, Alsenborn-Pfalz, Germany, assignors to G. M. Pfaff A.G., Kaiserslautern, Pfalz, Germany Filed Oct. 8, 1963, Ser. No. 314,707 Claims priority, application Germany, Oct. 13, 1962, P 30,353

The invention relates to sewing machines and is particularly concerned with looper drive means for sewing machines. More in particular, the invention relates to looper drive means for chain stitch sewing machines having adjustable bottom and needle feed means where the looper effects longitudinal loop seizing and dropping movements and lateral needle evading movements derived from two cams arranged upon the looper drive shaft.

In known chain stitch machines equipped with a com pound feed the looper swings parallel relative to the direction of feed. The looper point faces in the direction that is opposite to the direction of feed of the needle. A loop spreader must cooperate with the looper which is reciprocably movable perpendicularly to the direction of feed which seizes the looper thread and expands it in order to form, together with the preceding needle thread loop, the conventional thread triangle for the passage of the descending needle. The threading of the looper thread is not readily possible with this type of looper drive. The looper must first be swung aside into a position that is favorable for the needle threading operation.

The seizing of the looper thread by the loop spreader is considerably more diificult in a machine having compound feed than in a machine where the needle is moved up and down along a straight line, because the stitch hole is in the material feed dog that is moved back and forth in the direction of feed. With this type of feed dog movement a loosening occurs in the looper thread leg that is to be seized by the loop spreader, as a result of which this leg of the thread is without control and can move out of the effective range of the spreader, so that defective stitches are formed. The correct setting of the loop spreader must be carefully made by a man skilled in the art and requires considerable expenditure of time. Moreover, the thread is subject to considerable wear by the loop spreader, particularly in connection with rapidly operating sewing machines.

The forming of accurate chain stitches requires essentially that the distance of the looper from the needle and the upward movement or rise of the loop is always substantially equal during the seizing of the loop and that the forming of the thread triangle insures of accurate piercing by the needle. With sewing machines of the compound feed type and with a conventional looper drive, these stitch formation requirements differ for each stitch length.

In chain stitch machines provided with compound feed where the looper is moved in the direction opposite to the feed movement of the needle for seizing the needle thread loop, the looper and the needle move in the same direction during the loop dropping movement. Prior to the eye of the needle rising above the point of the looper, the looper must move to the end of its loop dropping thrust and then advance in a relatively short time to the loop seizing position. However, since the looper effects an unchanged, uneven oscillatory movement by means of a crank and rocking slide drive, while the advancing of the needle is varied with the change of the stitch length, the seizing of the loop by the looper 8 Claims.

point takes place with each different stitch length at a different distance from the eye of the needle. As a result also the magnitude of the loop rise differs. In order to prevent what is referred to as falling over of the loop, it is necessary to provide an additional loop support on the looper.

It is therefore an object of the invention to provide a looper drive for chain stitch machines of the compound feed type where the normally complicated looper spreading means as well as the looper support are eliminated, where furthermore the cooperation of the looper with the needle is influended by a device in a manner that the location of the entrance of the looper point into the needle thread loop formed during the upward movement of the needle is for all adjustable feed magnitudes of the needle at the same distance from the eye of the needle and from the center of the needle, while the needle loop rise is substantially equal.

In accordance with the invention this problem is solved in that for seizing the needle thread loop, the looper and the needle effect synchronized oscillatory movements in the direction of material feed and the angular position of the eccentric controlling the longitudinal movements can be changed upon the looper drive shaft by means of an adjusting device in such a manner that the looper point moves along a path which is adapted to the length of feed of the needle to provide stitch forming conditions which remain the same.

In accordance with a further object of the invention the angular position of the eccentric or cam for the longitudinal movements with respect to the eccentric for the needle evading movements is adjustable by one setting means upon the looper drive shaft in relation to the adjustable feed lengths of the needle and can be fixed in position by a latching device. By adjusting the angular position of the main eccentric or cam in relation to the feed length of the needle at any time, the peripheral line of the elliptical path of movement which is produced by the cooperation of the two drive cams is adjusted in such a manner that the distance of the needle from the looper point as it enters the thread loop corresponds to the needle distance which has been established to be correct; furthermore, by changing the angular position of the cam for the longitudinal movements the location of loop seizing by the looper point is adapted to the magnitude of feed of the needle, and finally by changing these two control points that are essential for chain stitch machines, the formation of the thread triangle is advantageously afiected, so that approximately equal stitch forming conditions are created for all adjustable feed lengths of the needle.

In accordance with a further object of the invention an advantageous construction of the adjusting device that is set by means of a setting disk is obtained in that the eccentric acted upon by the adjusting device is arranged at one end of a sleeve journalled coaxially with the looper drive shaft, to the other end of which sleeve a setting fork is secured in which a sliding block is guided that is journalled upon an eccentric stud of a pivotable bolt arranged parallel at a distance with respect to the looper drive shaft, and a fork is fastened upon the rocking shaft for a detent that is rigidly connected on a setting disk arranged coaxially with respect to the looper drive shaft.

A suitable latching means for the setting device is obtained in that a lever is mounted upon the pivotable bolt which has a spring biased catch bolt for recesses in a latch disk corresponding to the adjustable feeding lengths of the needle.

In accordance with a further object of the invention the setting disk is secured on the latch disk with elastic mounting means therebetween, so that the adjusting of the arrangement is made possible without previously loosening the setting screws.

In the further development of modern sewing machines endeavors are made to combine the setting devices in order to quickly and rapidly provide for adjusting to different types of sewing operations with a minimum of manual adjusting means on the machine. It is of particular significance in chain stitch sewing machines with compound feed where, as is well known, the deviation of the needle also changes the location of the seizing of the loop by the looper point, that simultaneously with the setting for a predetermined stitch length the looper oscillation derived from a cam is adapted to the adjusted stitch length. I

In accordance with a further object of the invention this is accomplished in that the setting means is connected with the material feed shaft. In this manner the angular position of the eccentric upon the looper drive shaft is adjustable by means of the setting means to correspond to the rhythm of the needle feed movement.

From an engineering standpoint a very advantageous solution of the problem is provided in that the setting means that is coupled by means of a link to the material feed shaft has a toothed mating gear rotatably mounted upon an oscillating frame on a shaft which is in operative connection with a toothed gear upon the looper drive shaft and which, together with the rocking frame, is pivotally movable about the looper drive shaft in the manner of a planetary wheel as determined by the adjustable fee-d lengths of the needle and is connected by way of a parallel crank drive with the sleeve of the eccentric.

The oscillatory movement of the mating or counter Wheel which depends on the material feed causes a relative movement between the two toothed gears, as a result of which an uneven rotary impulse is imparted to the drive eccentric for the looper which is reflected at the looper in a manner that an additional accelerated and delayed movement is superimposed on the uneven oscillatory movement of the looper point, while the evading or deflecting movement of the needle remains constant for all stitch-lengths.

The looper drive is coordinated in such a manner that,

depending on the stitch length, the looper point covers paths of different lengths for equal needle deflections during the same unit of time. As a result the needle distance remains equal for each stitch length while the loop rise is approximately equally great. In order to overcome the dead point as the unequal rotation of one toothed gear is transmitted to the sleeve of the eccentric, two eccentrics of the parallel crank drive are provided on each, the shaft and the sleeve, the phases of which are displaced. Further objects and advantages of the invention as well as details of the structure will become apparent from the following description of two embodiments of the invention and with reference to the accompanying drawings, in which:

FIG. 1 is a front view of the machine, partly in section,

FIG. 2 is a perspective view of the looper drive in accordance with FIG. 1,

FIG. 3 shows the looper drive provided below the base plate and a different embodiment of the setting means,

FIG. 4 is a perspective view of the looper drive With the setting means illustarted in FIG. 3,

FIG. 5 and FIG. 6 illustrate to an enlarged scale a part of the courses of movement of the needle and of the looper point for greatest and smallest stitch length, and

FIG. 7 illustrates parts of the courses of movement of the looper point for greatest and smallest stitch length while using the setting means shown in FIGS. 3 and 4.

The work plate 21 of the machine supports the housing 22 which ends in a head 23. In the housing 22 the arm shaft 24 is rotatably journalled in the arm shaft sleeves 25, 26, 27. At one end of the arm shaft 24 the balance wheel 28 and the belt pulley 29 are mounted. The arm shaft 24 is driven .by motor (not shown) and a belt extending over the belt pulley 29. At the end of the arm shaft 24 which extends into the head 23 the arm shaft crank 30 is secured which drives the needle bar 35 that is reciprocably movable in the needle bar oscillator or rocker 34 by way of the stud'31, link 32, and the needle bar stud 33. At the lower end the needle bar 35 supports the needle 36. The needle bar oscillator or rocker 34 is mounted for pivotal movement in the direction of feed on the stud 37 which is secured to the machine. The rocking shaft 38 with the rocking crank 39 is mounted in the housing 22 parallel to and at a distance from the arm shaft 24 and carries the slide block 41 on the stud 40. The slide block 41 extends into the guide groove 42 of the needle bar oscillator or rocker 34. The eccentric fork 43 is mounted on the rocking shaft 38 and encompasses the slide member 44 that is mounted upon an adjustable eccentric 45. The eccentric 45 is mounted upon the arm shaft 24 and has a setting ring 47 which has a retaining groove 46. The housing 22 is closed by means of a cover 48. An axially displaceable retaining pin 50 for the setting ring 47 is provided in the cover 48 that is biased by the spring 49 and movable against the force of that spring. The pin 50 has a stud portion which for adjusting the eccentricity engages the groove 46 as the retaining pin 50 is pressed downwardly.

Furthermore the crank 51 is secured to the rocking shaft 38 to which one end of the link bar 52 is connected which at the other end is linked to the crank 54 secured to the material feed shaft 53 that is journalled below the work plate 21.

The balance wheel 28 is provided with markings (11 different magnitudes in the first embodiment) to provide for convenient setting of the deflection of the needle 36 that may be rocked in the direction of feed. The feed dog 55 operates in synchronism with needle 36 and is mounted upon the feed bar 56 which is linked to a crank 57 that is secured to the feed shaft 53. A raising cam (not illustrated) imparts the necessary lifting impulses to the feed bar 56. The conventional presser foot that cooperates with the material feed dog 55 is not shown.

The drive means for the looper 59 mounted in the looper support 58 is arranged in a housing 60 below the material supporting or base plate 21. The looper drive shaft 61 journalled in the housing 60 is driven by the arm shaft 24 by way of the cord belt pulleys 62, 63, the belt 64, the shaft 65 and flange 66 which is provided with a key 67 that projects into a groove 68 in a coupling disk 69.

The elliptical looper movement is constituted of two individual movements, i.e., the needle deflection movement and the loop seizing and dropping movement.

For producing the needle deflection movement the eccentric 70 is secured to the looper drive shaft 61. The eccentric movement is imparted to the looper shaft by Way of a link bar 71, a bell crank lever 73 pivotable about a stationary axis of rotation 72 and a block 77 extending in the sliding groove 74 of a crank 76 secured to the looper shaft 75.

The coupling disk 69 is a part of a setting device indicated at 78 (FIGS. 1 and 2). In order to produce the loop seizing and dropping movement of the looper 59 the setting device 78 has a sleeve 79 mounted upon the looper drive shaft 61 and upon which an eccentric 80 is provided. The eccentric movement is transferred to the looper shaft 75 by way of an eccentric bar 81, a pivot pin 82 and the crank 76 which is secured to the looper shaft 75.

A bifurcated member 83 is secured to the sleeve 79 and engages a sliding block 84 which is rotatably journalled on an eccentric extension 85 of a pivot bolt 86. The bolt 86 is rotatably journalled in a journal boss 87 and in the flange 88 of the coupling disk 69. Between the journal boss 87 and the flange 88 an index crank 89 is secured upon the pivot bolt 86 and receives a piston pin 90 which is spring biased and the conical end of which cooperates with bores 91 in the flange 88 of the cOupling disk 69 in order to fix the sleeve 79 in the positions which correspond to the number of the bores 91. A setting fork 92 is furthermore secured upon the pivot bolt 86 which cooperates with a detent pin 94 secured to a setting disk 93. The setting disk 93 is provided with a plurality of mounting bores 95 and secured to the flange 88 by means of screws 97 with helical springs 96 interposed therebetween. In lieu of helical springs 96 other elastic inserts may be used, for example, nests of spring disks. The screws 97 extend through the arcuate slots 98 in the setting disk 93. At the periphery of the flange 88 index marks 1-11 are provided (FIG. 1) which correspond to the adjustable stitch lengths. The setting disk 93 is provided with a scored mark for these markings.

The looper 59 is secured upon a support 58 clamped to the looper shaft 75 in a manner that the looper point faces in the direction of feed. As may be required, several loopers and needles may be provided. The drive connections of the looper 59 impart to it a rocking movement in the direction of feed and a needle evading movement essentially perpendicularly to the direction of feed. The looper 59 and the needle 36 effect synchronized rocking movements in the direction of feed for seizing the needle thread loop.

FIGS. 3 and 4 illustrate the looper drive in connection with a further embodiment of the setting means which is generally identified by numeral 99. This setting means 99 has a crank 100 secured to the material feed shaft 53 between the bifurcated arms 101, 102 of which a link bar 103 is journalled for pivotal movement about a pin 104. The other end of the link bar 103 is connected to a rod 105 which is journalled in a rocking frame 106. The rocking frame 106 is mounted for pivotal movement about the looper drive shaft 107 journalled in the material carrier plate 21 and secured against axial displacement by means of collars 108, 109. In this embodiment the looper drive shaft 107 is a unitary member which takes the place of the shafts 61, 65 in accordance with FIGS. 1 and 2. A toothed gear 110 is secured to the looper drive shaft 107 which meshes with a counter gear 111 secured to the shaft 105.

Two eccentrics 112, 113 are secured on the shaft 105 displaced 'by approximately 120 and are connected by way of eccentric bars 114, 115 to two phasially displaced eccentrics 116, 117 secured to the sleeve 79.

The looper drive as well as the remaining components of the sewing machine correspond to those illustrated in FIGS. 1 and 2.

The manner of machine operation by means of setting means 78 is first described.

For setting the desired stitch length the detent pin 50 is actuated against the force of the spring 49 into the retaining groove 46 of the setting ring 47. By rotating the balance wheel 28 the desired stitch length is adjusted at the eccentric 45 to the corresponding amount of eccentricity. The adjusted stitch length is indicated by the markings on the balance wheel 28. Upon release the spring 49 forces the pin 50 again out of the retaining groove 46.

Owing to the different deflection magnitudes of the needle in connection with the different stitch lengths in compound feed machines, the location where the loops are seized by the looper (FIGS. 5 and 6) is changed for each stitch length.

The setting device 78 (FIGS. 1 and 2) which is operatively connected with the looper 59 is provided for the purpose that the angular position of the main eccentric 80 is changed in relation to the magnitude of feed of the needle in such a manner that the position of the looper point as seen in the direction of feed with respect to needle 36 is adapted to any adjusted stitch length in order to obtain for each magnitude of feed a substantially equal loop rise S, S'-FIG. 5). Furthermore, it is accomplished in this manner that the path of movement of the looper point (A, BFIG. 6) is likewise adapted to the particular adjusted feed distance of the needle 36 in order to obtain the same needle distance for each stitch length (x, x'FIG. 6).

The setting of the eccentric is effected by turning the setting disk 93 which is accessible by turning over the machine. It is also possible, however, to provide setting means which permit making the adjustments above the material carrier plate 21. For this purpose a rather complicated releasable coupling is required. The detent pin 94 of the setting disk 93 which extends into the setting fork 92 imparts an angular movement to the pivot bolt 86. The piston pin of the index crank 89 engages one of the bores 91. The angular position of the eccentric 80 secured to the sleeve 79 is changed with respect to the eccentric 70 by way of the eccentric extension 85, the sliding block 84 and the fork member 83, whereby the setting of the looper 59 secured upon the looper shaft 75 is changed relative to the needle 36 by way of the eccentric bar 81, the pivot pin 82 and the crank 76.

The markings on the balance wheel 28 and on the flange 88 of the setting device 78 have corresponding index numbers (1 to 11) so that for each adjusted feeding length of the needle 36 a corresponding looper position can be conveniently and readily undertaken.

When the setting of the desired feed length of the feed dog, the needle 36 and a corresponding setting of the looper 59 have been completed, it is possible to sew. The belt pulley 29 secured upon the arm shaft 24 is driven by a motor (not shown) by way of a belt. The arm shaft crank 30 moves the needle bar 35 up and down by way of pin 31, link 32 and the needle bar stud 33. The rocking shaft 38 has imparted to it rocking movements in the direction of feed by way of the eccentric 45, the slide member 44 and the fork member 43, which movements are transmitted by way of crank 39' and the stud 40 upon the slide block 41 onto the needle bar rocker 34. Simultaneously also the material feed shaft 53 receives the same rocking movement by way of the crank 51, secured to rocking shaft 38, link bar 52, and crank 54. As a result the needle 36 and the feed dog 55 execute feed movements of equal magnitude.

The coupling shaft 65 is operatively connected to the arm shaft 24 by way of belt pulleys 62, 63 and the chain belt 64. The coupling shaft 65 operates at the same number of rotations as the arm shaft 24 and by way of coupling 66, 67, 68 moves along the looper drive shaft 61 with the setting means 78.

The eccentric 80 secured to the sleeve 79 imparts a rocking movement C in the feed direction V (FIG. 5) to the looper 59 secured upon looper shaft 75 by way of eccentric bar 81, pivot pin 82 and crank 76. Besides this rocking movement C a needle deflection movement is imparted to the looper which is derived from the eccentric 70 by way of link bar 71, bell crank lever 73, slide block 77 and crank 76. Owing to the combined effect of both movements C and N, the looper 59 is moved along a path A, B of elliptic configuration.

The paths of movement of the needle 36 and of the looper eye are graphically illustrated in FIGS. 5 and 6 for greatest and smallest stitch length to a considerably enlarged scale.

In FIG. 5 the direction of feed is indicated by the arrow V. The curved line indicated at A shows the path of movement of the needle point for the largest stitch length, and the curved line B indicates the path of movement of the needle point for the smallest stitch length. A part of the needle rise is subdivided from 0-12 (Graph A) and 0'12' (Graph B). In order to illustrate the cooperation of the looper 59- with the needle 36 for largest and smallest stitch lengths, the points 1 to 12 for largest stitch length and the points 1' to 12' for smallest stitch length are marked on the graph C. The individual points indicate the locations where the looper point is located the positions where the looper point is located when the needle point indicated in graph A (FIG. 5) is in the position identified by the same numeral. In graph B numerals 1'-12 indicate the positions where the looper point is located when the needle point is in the position identified in graph B (FIG. 5) by the same numeral.

The points E and E' in FIGS. 5 and 6 identify the locations of the loop seizing by the looper point for the greatest and smallest stitch length.

FIGS. 5 and 6 reflect that for stitch lengths of different magnitude the looper point is in different positions relative to the center of the needle bar (center axis of the stud screw 37) along the elliptical path (A, B). This setting of the looper 59 is effected with the setting means 78 by rotating the setting disk 93. In this manner it is accomplished that the loop rise (indicated in FIG. 5 at S for largest stitch length and at S for smallest stitch length) will be almost equal for all stitch lengths. The difference between the loop rise for largest and for smallest stitch length amounts only to fractions of a millimeter and is practically of no consequence because normally the sewing is in the central region of the stitch length.

Furthermore, this adjustment also causes changes in the elliptic path of movement of the looper point for each stitch length (in FIG. 6 indicated at A for largest .and B for smallest stitch length), in such a manner that the distance between the looper point with respect to the center of the needle (x for largest, x for smallest stitch length, FIG. 6) is always of the same magnitude. By the phase displacement of the looper 59 with respect to the stitch length, the entrance of the needle 36 into the thread triangle (which is known and therefore not shown), as related to the looper blade and the looper eye, contrary to other chain stitch machines with compound feed where the needle entrance as related to the looper eye is displaced for different stitch lengths, takes place with all stitch lengths provided by the sewing machine in accordance with the invention always at the same location between legs of the thread triangle which are formed by the needle thread loop, beginning with the last stitch entrance and extending around the neck of the looper, and the looper thread extending from the last stitch entrance to the looper eye. As a result, reliable needle entrance into the thread triangle is safeguarded for all stitch lengths without a loop spreader requiring its own operating means for holding open the thread triangle.

While the setting means 78 must be changed manually .as the stitch length is changed, the setting means 99 is connected by the link bar 103 directly with the feed dog 55. In this manner the setting means 99 adjusts itself automatically to the magnitude otf feed of the feed dog 55 and of the needle 36, in which connection it should be noted that the feed dog and needle effect feed movements of equal magnitude.

When the arm shaft 24 rotates, the rocking shaft 38 has a rocking movement imparted to it by way of eccentric 45, the slide block 44 and the eccentric 43 which is transmitted to the rocking frame 34 by way of the rocking crank 39, the stud 40, and the slide block 41.

Simultaneously also the material feed shaft 53 has imparted to it the same rocking movement by Way of the [and the crank 54 which is transmitted by way of the connecting bar 103 to the rocking frame 106, having as a pivot axis the looper drive shaft 107. The toothed gear 111 mounted on the shaft 105 is angularly displaced thereby in the manner of a planet wheel about the toothed gear secured to the shaft 107 operatively connected thereto by way of the chain wheels 62, 63 and the cord chain 64 and has in this manner imparted to it an accelerated rotary movement in one direction of rotation and a retarded rotary movement in the other direction of rotation. This rotary movement is transmitted by eccentric 112, 113 secured to the shaft 105, eccentric bars 114, .115 and the eccentrics 116, 117 onto the sleeve 79 by means of the drive eccentric 80 mounted thereon. The angular position of the eccentric 80 is thereby changed with resepct to the rhythm of the feed movement. The eccentric 80 imparts to the looper 59 secured on the support 58 an uneven rocking movement in the direction of feed which is accelerated and retarded depending on the magnitude 'of feed by way of eccentric bar 81, pivot stud 82 and the crank 76 mounted upon the looper shaft 75. The needle deflecting movement of the looper derived from eccentric 70 which is perpendicular to the direction of feed remains constant in this connection.

By the cooperation of the looper drive connections and the setting means 99 the looper point is moved in this embodiment along an elliptic path indicated in FIG. 7 at A" for maximum feed legth and at B" for minimum feed length.

As shown in FIG. 7 the path which is described by the looper point from its forward reversing position (U,

U) to the loop seizing position :(E, E) is greater with a large feed movement (U-E) than for a small stitch (UE'). When the needle distance x or x and the loop rise (8-8) are to be approximately of the same magnitude, the l-ooper point must pass through these different stretches (U-E, -U-E during the same period of time. This is made possible in that the looper 59 is in operative connection with the setting means 99 by means of which, depending on the magnitude of feed, the acceleration of the looper 59 is also changed. In FIG. 7, 0-12 or O-12' indicate those points where the looper point is disposed when the needle point is at the points indicated in FIG. 5 at O12 or O12'.

Having now described our invention with reference to the embodiments illustrated in the drawings, we do not wish to be limited thereto, but what we desire to protect by Letters Patent of the United States of America is set forth in the appended claims.

We claim:

1. In a chain stitch sewing machine having a machine arm, a base plate and adjustable bottom and needle feed means of the type in which the looper effects longitudinal thread seizing and dropping movements and lateral needle deflecting movements derived from eccentrics, a looper drive mechanism including synchronizing means and setting means for imparting adjustable movements to the looper to synchronize the looper with the needle, said synchronizing means comprising an arm shaft journalled in said machine arm, a needle bar supporting a needle disposed endwise of said arm shaft, a rocker for guiding said needle bar, a rocking shaft, means operatively linking said rocking shaft to said arm shaft and to'said rocker, a looper drive shaft disposed below the base plate, means operatively connecting said looper drive shaft to said arm shaft, a looper shaft, a looper connected to said looper shaft and disposed below said needle and linkage means including a first adjustable eccentric mounted on said looper drive shaft for effecting longitudinal thread seizing and dropping movements, said first eccentric linking said looper shaft to said looper drive shaft, and a second eccentric mounted on said looper drive shaft and operatively associated with said looper shaft for controlling deflecting movements of said looper, and said setting means including adjustable means mounted concentrically with said looper drive shaft, said adjustable means being operatively interconnected with the first adjustable eccentric operative to change the angular position of said first eccentric for coordinating the longitudinal movements and the deflecting movement of said looper to establish coincidence of looper movements with respect to the adjustable needle feed means for different stitch lengths.

2. In a chain stitch sewing machine having a machine arm, a base plate and adjustable bottom and needle feed means of the type in which the looper effects longitudinal thread seizing and dropping movements and lateral needle deflecting movements derived from eccentrics, a looper drive mechanism including synchronizing means and setting means for imparting adjustable movements to the looper to synchronize the looper with the needle, said synchronizing means comprising an arm shaft journalled in said machine arm, a needle bar supporting a needle disposed endwise of said arm shaft, a rocker for guiding said needle bar, a rocking shaft, means operatively linking said rocking shaft to said arm shaft and to said rocker, a looper drive shaft disposed below the base plate, means operatively connecting said looper drive shaft to said arm shaft, a looper shaft, a looper connected to said looper shaft and disposed below said needle and linkage means including a first adjustable eccentric mounted on said looper drive shaft for effecting longitudinal thread seizing and dropping movements, said first eccentric linking said looper shaft to said looper drive shaft, and a second eccentric mounted on said looper drive shaft and operatively associated with said looper shaft for controlling deflecting movements of said looper, and said setting means including adjustable means mounted concentrically with said looper drive shaft, said adjustable means being operatively interconnected with the first adjustable eccentric operative to change the angular position of said first eccentric for coordinating the longitudinal movements and the deflecting movement of said looper to establish coincidence of looper movements with respect to the adjustable needle feed means for different stitch lengths, and said setting means including a pair of disks movable relative to one another and detent means for retaining said disks in adjusted position.

3. In a chain stitch sewing machine having a machine arm, a base plate and adjustable bottom and needle feed means of the type in which the looper effects longitudinal thread seizing and dropping movements and lateral needle deflecting movements derived from eccentrics, a looper drive mechanism including synchronizing means and setting means for imparting adjustable movements to the looper to synchronize the looper with the needle, said synchronizing means comprising an arm shaft journalled in said machine arm, a needle bar supporting a needle disposed endwise of said arm shaft, a rocker for guiding said needle bar, a rocking shaft, means operatively linking said rocking shaft to said arm shaft and to said rocker, a looper drive shaft disposed below the base plate, means operatively connecting said looper drive shaft to said arm shaft, a looper shaft, a looper connected to said looper shaft and disposed below said needle and linkage means including a first adjustable eccentric mounted on said looper drive shaft for effecting longitudinal thread seizing and dropping movements, said first eccentric linking said looper shaft to said looper drive shaft, and a second eccentric mounted on said looper drive shaft and operatively associated with said looper shaft for controlling deflecting movements of said looper, and said setting means including adjustable means mounted concentrically 'with said looper drive shaft, said adjustable means being operatively interconnected with the first adjustable eccentric operative to change the angular position of said first eccentric for coordinating the longitudinal movement and the deflecting movements of said looper to establish coincidence of looper movements with respect to the adjustableneedle feed means for different stitch lengths, said setting means including a pair of disks movable relative to one another and detent means for retaining said disks in adjusted position, and a sleeve mounted around said looper drive shaft, said adjustable eccentric being mounted on one end of said sleeve and the other end of said sleeve being operatively connected to said disks by means including a first bifurcated member, a sliding block in engagement with said first bifurcated member, a pivot bolt extending parallel to the looper drive shaft having one end in engagement with said disks and having an eccentric member in engagement with said sliding block, a second bifurcated member mounted at the other end of said pivot bolt and a detent on one said disk in sliding engagement with said second bifurcated member.

4. In a chain stitch sewing machine having a machine arm, a base plate and adjustable bottom and needle feed means of the type in which the looper effects longitudinal thread seizing and dropping movements and lateral needle deflecting movements derived from eccentrics, a looper drive mechanism including synchronizing means and setting means for imparting adjustable movements to the looper to synchronize the looper with the needle, said synchronizing means comprising an arm shaft journalled in said machine arm, a needle bar supporting a needle disposed endwise of said arm shaft, a rocker for guiding said need-1e bar, a rocking shaft, means operatively linking said rocking shaft to said arm shaft and to said rocker, a looper drive shaft disposed below the base plate, means operatively connecting said looper drive shaft to said arm shaft, a looper shaft, a looper connected to said looper shaft and disposed below said needle and linkage means including a first adjustable eccentric mounted on said looper drive shaft for effecting longitudinal thread seizing and dropping movements, said first eccentric linking said looper shaft to said looper drive shaft, and a second eccentric mounted on said looper drive shaft and operatively associated with said looper shaft for controlling deflecting movements of said looper, and said setting means including adjustable means mounted concentrically with said looper drive shaft, said adjustable means being operatively interconnected with the first adjustable eccentric operative to change the angular position of said first eccentric for coordinating the longitudinal movements and the deflecting movements of said looper to establish coincidence of looper movements with respect to the adjustable needle feed means for different stitch lengths, said setting means including a pair of disks movable relative to one another and detent means for retaining said disks in adjusted position, and a sleeve mounted around said looper drive shaft, said adjustable eccentric being mounted on one end of said sleeve and the other end of said sleeve being operatively connected to said disks by means including a first bifurcated member, a sliding block in engagement with said first bifurcated member, a pivot bolt extending parallel to the looper drive shaft having one end in engagement with said disks and having an eccentric member in engagement with said sliding block, a second bifurcated member mounted at the other end of said pivot bolt and a detent on one said disk in sliding engagement with said second bifurcated member, and a lever member mounted on said pivot bolt including a spring biased piston pin, the other said disk being a flange having a plurality of recesses for engagement with said piston pin.

5. In a chain stitch sewing machine having a machine arm, a base plate and adjustable bottom and needle feed means of the type in which the looper effects longitudinal thread seizing and dropping movements and lateral needle deflecting movements derived from eccentrics, a looper drive mechanism including synchronizing means and setting means for imparting adjustable movements to the looper to synchronize the looper with the needle, said synchronizing means comprising an arm shaft journalled in said machine arm, a needle bar supporting a needle disposed endwise of said arm shaft, a rocker for guiding 1; 1 said needle bar, a rocking shaft, means operatively linking said rocking shaft to said arm shaft and to said rocker, a looper drive shaft disposed below the base plate, means operatively connecting said looper drive shaft to said arm shaft, a looper shaft, a looper connected to said looper shaft and disposed below said needle and linkage means including a first adjustable eccentric mounted on said looper drive shaft for effecting longitudinal thread seizing and dropping movements, said first eccentric linking said looper shaft to said looper drive shaft, and a second eccentric mounted on said looper drive shaft and operatively associated with said looper shaft for controlling deflecting movements of said looper, and said setting means including adjustable means mounted concentrically with said looper drive shaft, said adjustable means being operatively interconnected with the first adjustable eccentric operative to change the angular position of said first eccentric for coordinating the longitudinal movements and the deflecting movements of said looper to establish coincidence of looper movements with respect to the adjustable needle feed means for different stitch lengths, said setting means including a pair of disks movable relative to one another and detent means for retaining said disks in adjusted position, and a sleeve mounted around said looper drive shaft, said adjustable eccentric being mounted on one end of said sleeve and the other end of said sleeve being operatively connected to said disks by means including a first bifurcated member, a sliding block in engagement with said first bifurcated member, a pivot bolt extending parallel to the looper drive shaft having one end in engagement with said disks and having an eccentric member in engagement with said sliding block, a second bifurcated member mounted at the other end of said pivot bolt and a detent on one said disk in sliding engagement with said second bifurcated member, and a lever member mounted on said pivot bolt including a spring biased piston pin, the other said disk being a flange having a plurality of recesses for engagement with said piston pin, and elastic means including a screw and a spring securing said one disk to said 6. In a chain stitch sewing machine having a machine arm, a base plate and [adjustable bottom and needle feed means of the type in which the looper effects longitudinal thread seizing and dropping movements and lateral needle deflecting movements derived from eccentrics, a looper drive mechanism including synchronizing means and setting means for imparting adjustable movements to the looper to synchronize the looper with the needle, said synchronizing means comprising an arm shaft journalled in said machine arm, a needle bar supporting a needle disposed endwise of said arm shaft, a rocker for guiding said needle bar, a rocking shaft, means operatively linking said rocking shaft to said arm shaft and to said rocker, a looper drive shaft disposed below the base plate, means operatively connecting said looper drive shaft to said arm shaft, a looper shaft, a looper connected to said looper shaft and disposed below said needle and linkage means including a first adjustable eccentric mounted on said looper drive shaft for effecting longitudinal thread seizing and dropping movements, said first eccentric linking said looper shaft to said looper drive shaft, and a second eccentric mounted on said looper drive shaft and operatively associated with said looper shaft for controlling defleeting movements of said looper, and said setting means including adjustable means mounted concentrically with said looper drive shaft, said adjustable means being operatively interconnected with the first adjust-able eccentric operative to change the angular position of said first eccentric for coordinating the longitudinal movements and the deflecting movements of said looper to establish coincidence of looper movements with respect to the adjustable needle feed means for different stitch lengths, said sewing machine including a feed dog shaft and said setting means including a link bar pivotally connected to said feed dog shaft.

7. A looper drive mechanism for use in a chain stitch sewing machine in accordance with claim 3, wherein said setting means comprises a gear on said looper drive shaft, a rocking frame, a pivot rod mounted on said rocking frame supporting a counter gear in engagement with said gear on said looper drive shaft and movable in the manner of a planet gear in accordance with the feed magnitudes to which said feed dog shaft and said needle are adjusted, and linkage means including eccentrics connecting said pivot rod to said sleeve.

8. A looper drive mechanism for use in a chain stitch sewing machine in accordance with claim 3, wherein said setting means comprises a gear on said looper drive shaft, a rocking frame, a pivot rod mounted on said rocking frame supporting a counter gear in engagement with said gear on said looper drive shaft and movable in the manner of a planet gear in accordance with the feed magnitudes to which said feed dog shaft and said needle are adjusted, and linkage means including eccentrics connecting said pivot rod to said sleeve, said linkage means being in the form of a parallel phase displaced parallel crank drive and comprising a pair of eccentrics on said pivot rod and a pair of eccentrics connected to said sleeve.

References Cited by the Examiner UNITED STATES PATENTS JORDAN FRANKLIN, Primary Examiner.

R. I. SCANLAN, JR., Assistant Examiner. 

1. IN A CHAIN STITCH SEWING MACHING HAVING A MACHINE ARM, A BASE PLATE AND ADJUSTABLE BOTTOM AND NEEDLE FEED MEANS OF THE TYPE IN WHICH THE LOOPER EFFECTS LONGITUDINAL THREAD SEIZING AND DROPPING MOVEMENTS AND LATERAL NEEDLE DEFLECTING MOVEMENTS DERIVED FROM ECCENTRICS, A LOOPER DRIVE MECHANISM INCLUDING SYNCHRONIZING MEANS AND SETTING MEANS FOR IMPARTING ADJUSTABLE MOVEMENTS TO THE LOOPER TO SYNCHRONIZE THE LOOPER WITHE THE NEEDLE, SAID SYNCHRONIZING MEANS COMPRISING AN ARM SHAFT JOURNALLED IN SAID MACHINE ARM, A NEEDLE BAR SUPPORTING A NEEDLE DISPOSED ENDWISE OF SAID ARM SHAFT, A ROCKER FOR GUIDING SAID NEEDLE BAR, A ROCKING SHAFT, MEANS OPERATIVELY LINKING SAID ROCKING SHAFT TO SAID ARM SHAFT AND TO SAID ROCKER, A LOOPER DRIVE SHAFT DISPOSED BELOW THE BASE PLATE, MEANS OPERATIVELY CONNECTING SAID LOOPER DRIVE SHAFT TO SAID ARM SHAFT, A LOOPER SHAFT, A LOOPER CONNECTED TO SAID LOOPER SHAFT AND DISPOSED BELOW SAID NEEDLE AND LINKAGE MEANS INCLUDING A FIRST ADJUSTABLE ECCENTRIC MOUNTED ON SAID LOOPER DRIVE SHAFT FOR EFFECTING LONGITUDINAL THREAD SEIZING AND DROPPING MOVEMENTS, SAID FIRST ECCENTRIC LINKING SAID LOOPER SHAFT TO SAID LOOPER DRIVE SHAFT AND SECOND ECCENTRIC MOUNTED ON SAID LOOPER DRIVE SHAFT, AND A OPERATIVELY ASSOCIATED WITH SAID LOOPER SHAFT FOR CONTROLLING DEFLECTING MOVEMENTS OF SAID LOOPER, AND SAID SETTING MEANS INCLUDING ADJUSTABLE MEANS MOUNTED CONCENTRICALLY WITH SAID LOOPER DRIVE SHAFT, SAID ADJUSTABLE MEANS BEING OPERATIVELY INTERCONNECTED WITH THE FIRST ADJUSTABLE ECCENTRIC OPERATIVE TO CHANGE THE ANGULAR POSITION OF SAID FIRST ECCENTRIC FOR COORDINATING THE LONGITUDINAL MOVEMENTS AND THE DEFLECTING MOVEMENT OF SAID LOOPER TO ESTABLISH COINCIDENCE OF LOOPER MOVEMENTS WITH RESPECT TO THE ADJUSTABLE NEEDLE FEED MEANS FOR DIFFERENT STITCH LENGTHS. 